Updates to The Standards and Industry Practice Around Gas Detection

Updates to The Standards and Industry Practice Around Gas Detection

31 Aug 2017, 11:35 AM - 12:20 PM

Sydney Showground, Sydney Olympic Park

Language:

English (Australia)

Accurate gas sensing is a critical element of safety systems for underground mines or confined spaces. Whether it is a hazardous atmosphere with monitoring for explosive risk, or monitoring toxicity to ensure acceptable exposure limits for underground personnel, all mines are required to implement and maintain a comprehensive environmental monitoring system.

Until recently, both Standards and industry practice focused almost exclusively on the absolute accuracy of a gas sensor as the most important instrumentation feature. Most mines implement a comprehensive program of maintenance for gas detectors with regular bump testing through to scheduled NATA calibration – the vast majority of this effort is about ensuring absolute accuracy of the detector reading. It is not typical practice to test the instrument’s time (or transient) response in the field. Both NSW and QLD Inspectorates have recently released notices about the importance of time response testing.

The new revision of AS2290.3 (Maintenance of Gas Detectors and Monitoring) will introduce the need for time response testing of gas detectors in the field. However, the interaction of time response and absolute accuracy for some gas detection technology in widespread use is poorly understood.

Are you aware that a sensor that is compromised in terms of time response:

• will still calibrate correctly and to sufficient accuracy when bump tested?

• can under report the actual ambient gas concentration in still air?

• can read incorrectly in the presence of moving ventilation air?

• will increase operating risk substantially being unable to respond to transient gas bursts and increase the delay to alarm?

Ampcontrol frequently receives gas detectors from operating mines in an unsatisfactory condition despite the detectors being routinely maintained and within NATA calibration windows.

The presentation will overview the importance of both transients (step response) as well as absolute accuracy in ensuring a gas detector is functioning correctly. The presentation is supplemented with video footage to demonstrate simple, practical testing suitable for use in the field to validate a detectors time response as part of the normal calibration process. We will discuss common pitfalls in measurement of transient response time, as well as the importance of utilising OEM endorsed calibration equipment.

Whilst many of the examples are related to coal operations, the maintenance principles discussed are equally applicable to metalliferous operations.

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